E-nose to sniff out hospital superbugs

By Paul Marks

AN ELECTRONIC nose that sniffs out infections could help hospitals tackle outbreaks of the antibiotic-resistant superbug MRSA.

Culture tests routinely used to identify MRSA (methicillin-resistant Staphylococcus aureus) take two or three days to complete. This hampers attempts to manage outbreaks as infected patients remain untreated and at risk of infecting others.

DNA-based tests are being trialled that promise to reduce test times to 2 hours, but now UK-based researchers have come up with a test using an electronic sniffer that could cut the time further, to just 15 minutes. Writing in the journal Sensors and Actuators B (vol 109, p 355), engineers at the University of Warwick and doctors at the Heart of England Hospital, Birmingham, say the electronic nose can recognise the unique cocktail of volatile organic compounds that S. aureus strains excrete.

E-noses analyse gas samples by passing the gas over an array of electrodes coated with different conducting polymers. Each electrode reacts to particular substances by changing its electrical resistance in a characteristic way. Combining the signals from all the electrodes gives a “smell-print” of the chemicals in the mixture that neural network software built into the e-nose can learn to recognise.

Each e-nose is about the size of a pair of desktop PCs and costs about £60,000. The food industry uses similar machines to root out rotten ingredients.

David Morgan, a surgeon at the hospital, says the idea of sniffing out superbugs came to him one day in the operating theatre. “I was operating on neck abscesses on two different patients and noticed their infections had slightly different smells, so I wondered if a machine ...

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